The Heathkit ET-3400 Microprocessor Trainer

In this video we take a look at the Heathkit ET-3400 Microprocessor Trainer, also referred to as the Microcomputer Learning System.

[_Huperniketes_]

I owned and assembled one of these babies! I’m jealous you have one!

Also, with the mechanical background noise, it sounds like I’m watching this on a projector back in elementary school! 😂

[jc_from_tx]

I trained on this in college back in 1990, after I graduated i made one using a wire wrap board from an obsolete process control system, programmed the rom and found a hex kybd from another device with Hall effect switches and it still works today!

[esra_erimez]

The importance of your videos cannot be overstated. Thank you.

[TheRadiogeek]

Fantastic job covering this Heathkit! Nice work getting that replacement ROM to work. 👍

[stever.]

Great job. As others here, I built one of these. Still have it, and I think 4 binders of educational materials - ALL put away. Each binder came with a pack of electronic components to do experiments with. I remember programming in assembly language, not "Machine Code"
Thank you - good memories.

[bsvenss]

Smart use of the hexadecimal keyboard. Logical and easy to remember.

[ALL_ONE_SUN]

YES to making an open source PCB clone of 3400 or 3400A!!! Thanks in advance!

[Philip]

Nice job! I admire your patience in entering the ROM code to check if it was the same!

[waaos]

Thank you Mr. Tranter for another well done video! I am also a Heathkit fan and have built many of their products. I really miss that company as it was in its glory days of the 60's - late 80's. I hope the new owners are able to continue some of it's innovative history and more cool kits. However now we are in the day or microminiaturization with tiny surface mount parts, it is doubtful that the average emerging electronics hobbyist will get to enjoy the thrill of building a Ham station, audio system or an 8-bit computer system.
Have you considered getting permission from the new owners to grade and issue Heathkit course certifications? Apparently, there are loads of Heathkit courses, many of them sold with the final exam. You could even issue new final exams to those who buy a course, take it but have no exam material. I bet it would be a good niche venture. At ~ $20 per exam and with your YT channel establishing your Heathkit product knowledge, etc, I could see this as a win win deal and away for newbies to learn electronics with a goal of collecting certificates.
As the owner of a small electronics company, I could see a new hire taking the basic courses in electronics, as away to make that person more valuable to my biz.

[RetroMarkyRM]

now that's what I call perfect preservation. Great stuff :)

[GaryCameron]

I still have mine in the basement. Soldered it all myself when I was 15.

[davidpeterson]

Great introduction to this device.
thanks

[colekeircom]

As the song goes, "thanks for the memories ", no pun intended . I spent about 5 evenings after work making this kit, so many years ago . Regards Kieron.

[flossflink]

Great commentary! You should make educational videos! You had me glued to this video the whole way. Nicely paced!

[MK-gemh]

At 3:00, you mention that the ET-3400A chips were upgraded to 1K, thus 1K of RAM was standard. That's only partially true. Though there were two 1Kx4-bit SRAM chips, only the first 512 bytes were decoded.

[rohnkdhct]

I remember using this when I was in college.

[RogelioPerea]

It's where I learned uP programming back in 1982, managed to acquire a 3400 a while back - still on the to-do list to install the updates required to hook it up to the accessory box.

[FluxCondenser]

Love your channel and all these Heathkit videos. One tiny complaint: The ruffling noise from your lapel (?) mic.

[flymario]

I have one of these as well in perfect condition. Not sure what to do with it. I daydream a lot of adding some hardware too it but it's not got one of my favorite CPUs like the 6502 or the Z80. Still though, it is such a nice unit. Glad things worked out for you and your machine!

[pauljansenpj]

I thoroughly enjoyed using the MC6800 processor in school as the first "low-level" type of programming that I had engaged and interfaced with. Previous courses used higher level languages such as FORTRAN and BASIC. An interface course at this level not only gave a much better understanding of things like memory layout, access, etc. but was my first experience interfacing with real world I/O such as TTL logic chips. The other recall I have is just how compact the programming can be when writing in opcode compared to a compiled or assembled language. It is also amazing how close to realtime one can get even with a relatively slow clock speed as only a few clock cycles are required per instruction and high priority type tasks could be easily managed through interrupt servicing. In retrospect, the entire system, with it's peripheral interfacing architecture, powerful addressing scheme, tristate bus and the ability to "micro-channel" I/O on the same clock pulse (uniquely configurable peripheral interface adapter or PIA) made this system an engineering marvel of it's time and allowed Motorola to venture into the industrial control world unrivaled by other microprocessor manufacturers of the time. Genius at work.